Admixtures

I understand your concern about the cracks in your garage, however, it is important to find out the reason for the cracks development.

In general it is a natural thing for concrete to crack.

The cracks that appear soon after the concrete is poured are most likely drying shrinkage cracks and are to be expected. If the cracks are, in fact, drying shrinkage there are a few things that can be done to minimize the possibility of cracking.

1) Use of concrete admixtures such as water reducers to lower the water cement ratio or use of shrinkage reducing admixture is recommended.
2) Addition of concrete fibers or reinforcement steel also reduces the possibility of shrinkage.
3) Proper curing is a must although it is very often forgotten.
4) Placement of control joints is always recommended. Control joints can be sealed afterwards with construction sealants to prevent the moisture and water penetration, which can cause problems especially during winter months.

Cracks developed due to drying shrinkage usually pose no structural threat even though they may be unsightly.

Another consideration is the possibility of sub-grade movement. If the cracks continue to get wider there may be movement of the base. If this is the case then saw cutting will do no good at this point. The only recommendation would be sub-grade stabilization. Removing and replacing the concrete is always an option but you may end up with the same cracks if this is not done.

If you decide to re-pour the garage, and you verify that cracks are not caused by sub-grade movements, I would suggest control joints to accommodate the drying shrinkage. It won’t stop the concrete from cracking but the cracks will be straight.

More information regarding the control of cracking in concrete structures can be found at ACI manual section 224R – 01.

Color pigments which are used in produce colored concrete products are generally available in liquid, powder or granulated form. You will find all the related information about the use of colors in concrete products on the color suppliers website or on the technical data sheets of their products.

Refer to the below weblink.

http://www.concreteproductsbuyersguide.com/Block__Landscape__Paver_Products_6175ea62.html

On the page of the web link, click on either “granulated”, “liquid” or “powdered” and it would give you the list of companies supplying colors in those forms.

Now, refer to the website of these companies and you should find all the information related to the use of colors in concrete like dosage rate, way of mixing, types of colors, packaging, precautions etc. To find the company website you can type the name of the company in Google.com.

Thanks and good luck.

Dear Fazz,

All your questions and concerns regarding the patent procedure can be answered by the United States Patent and Trademark Office. This office has all necessary information listed on their web site: http://www.uspto.gov/go/pac/doc/general/

There you will be able to find all the information needed for a successful patent process.

Without exact knowledge of your technology, before you do so, I would suggest you look up some more information about cellular concrete or lightweight concrete, as these products can be similar to your application.

In regards to production you will be required to meet certain criteria for this type of material such as strength, fire or health necessities. These and other testing requirements can be found at IBC (International Building Code), UBC (Uniformity Building Code) or you can find specifications in ASTM (American Society for Testing and Materials Standards). www.astm.org.

The question of matching existing color in concrete is difficult. If you match the existing color in time the new application will fade and be different. If you use the same color that was used in the original application you would have to wait for the new color to fade to be the same as existing color.

On a small job like a patio I would suggest the use of a concrete stain. With a stain you could apply it to both new and old concrete and have a fairly uniform color.

For large jobs a colorimeter could be used to match existing color but that would take a special order to manufacture. That would mean a commitment for a quantity large enough to justify a special production run. I don’t think a patio would be big enough.

If you wanted to place a topping concrete mix over the entire area and apply a dry shake colored floor hardener you could get uniform color. Or, an integral color could be put in a concrete overlay.

Other than topping I think a concrete stain would be your best bet.

Dear Mr. Alokjit,

This has reference to your question regarding "Admixtures for Precast FRP concrete".

The most commonly used polymer to make polymer modified concrete is a latex polymer, which is added to the concrete during mixing. Generally, the solid content of the latex polymer is in the range of 40 - 55%. The dosage range of solid polymer latex in concrete is from 10% to 25% by weight of cement depending on the properties desired.

Addition of latex polymer increases the workability of the concrete, so the water to cement ratio should be reduced appropriately. If you are looking for a higher water reduction than what is achieved by using the latex polymer, you can use either a water reducing or high range water reducing admixture. For more specific details on the dosage of the polymer and admixture, please follow the suppliers/ manufacturer's recommendations.

Polymer modified concretes have good resistance to water and have good bonding properties, so they popularly used for repair jobs or waterproofing jobs (eg. basement waterproofing)

If you are planning to use polymer in concrete to just improve its resistance to water ingress, another economical alternative would be to use either an integral waterproofing compound or a superplasticizer and reduce the water to cement ratio of the concrete to improve its water tightness. You can also use materials like Fly ash and slag at appropriate levels, which also help to reduce permeability.

Thanks and good luck.